Funding for this research was provided by:
U.S. Environmental Protection Agency (J6300100405)
Received: 2 January 2016
Accepted: 5 August 2016
First Online: 30 September 2016
Compliance with ethical standards
: This article does not contain any studies with human participants or animals performed by any of the authors.
: For this type of study formal consent is not required.
: The authors declare that they have no competing interests.